The present invention disclosed herein relates to a gas sensing apparatus, and more particularly, to a light absorption-type gas sensing apparatus and a method of sensing gas using the gas sensing apparatus.
Energy wavelengths corresponding to kinetic modes of gas molecules to be detected in environmental pollutant measuring, process gas monitoring, toxic gas detection, etc. are largely concentrated within the mid-infrared spectrum. Spectroscopic methods currently in use or under development typically employ thermo-resistive light sources or mid-infrared lasers. Particularly, when lasers are used, ultra-low concentrations of gas below one part per billion (ppb) can be detected, allowing for remote gas detection. Thus, research in the field of laser detection is vigorously being pursued.
For detecting highly-diluted gas with high sensitivity using detection chambers, an important point is for laser light to provide coverage broad enough to yield an adequate light absorption signal when contacting gas molecules. For this end, a method of lengthening the light beam path with multi-reflection, achieved by mounting mirrors within a detection chamber such as a white chamber, is widely used. However, this method has the limitation in that light intensity is reduced when reflected multiple times. Limiting the decrease in light intensity by reducing the number of times the light is reflected necessitates substantially increasing the length and volume of the chamber.